1. Field of the Invention
The invention refers to implantable medical devices (IMDs) providing means for determining and evaluating thoracic impedance. The preferred embodiment relates in particular to implantable cardiac pacemakers, cardiac resynchronization therapy devices, transplant rejection monitoring devices, or implantable cardioverter/defibrillators (ICD).
2. Description of the Related Art
This invention relates to an implantable medical device and a method of assessing pulmonary congestion usually associated with worsening heart failure. Heart failure (HF) can cause a build up of fluid in the lungs and body of a patient. Such an increase of fluid in the lungs can be determined by impedance monitoring as is, for example, disclosed in U.S. Pat. No. 5,876,353, U.S. Pat. No. 5,957,861 and U.S. Pat. No. 6,473,640.